1. Field of the Invention
The present invention relates to a character processing method in which closed outline coordinate information prepared as standard graphic information and outline information for use to distinguish a plurality of closed outlines included in the above-described information are enlarged or reduced by calculations before they are converted into dot information, the dot information being then converted into bit map development character data for use in an output character-processing apparatus.
2. Related Background Art
Recently, print (print block copy) processing systems arranged in accordance with an electronic method have been significantly widely used with an improvement in the cost performance of a microcomputer, progress of hardware such that a small and precise page printer and a precise monitor display have been popularized, and the substantiality of word processing software.
In the above-described system, the character image output technology, which is the most important factor for forming a print of excellent quality, must meet the following requirements:
As the first requirement, the system must be constituted in such a manner that beautiful characters of a variety of font sizes can be reproduced.
As the second requirement, the same must be constituted in such a manner that characters can be freely developed and decorations can be performed, the decorations being exemplified by italic type, elongating, flattening, shadowing and hatching (internal tiling), so that a free and appealing layout is realized.
As the third requirement, the above-described system must be arranged in such a manner that an image of a specified layout which is finally output from a printer can be directly confirmed (WYSIWYG=What You See Is What You Get) on, for example, a display.
In order to meet the above-described requirements, systems employing a character generating method (hereinafter called an "outline font method"), which is arranged on the basis of defining the outline points of the character image, have been widely used.
According to the outline font method, for example, coordinate data about the control point for expressing the outline of the character is previously prepared in a ROM (Read Only Memory) of the system. Then, in accordance with a character code index, it is read into a temporary storage device RAM (Random Access Memory) so as to be temporarily stored there. Then, in accordance with the specified character output size and the resolution of the output device such as a printer, the above-described coordinate data about the control point is mathematically enlarged or contracted by calculations. Then, it is converted into dot information so that a character can be generated while revealing improved freedom with respect to the output size of the character and the resolution of the output device such as a printer. It has been known that the above-described method is particularly able to form a character of a large size while maintaining improved image quality in comparison to the conventional dot-font character generating method.
However, the outline font method was developed in the first half of the 1960's so as to be adapted to a considerably expensive microfilm output system or a very large size print block copy output system.
That is, the above-described method has been developed so as to be adapted to a high resolution output device of, for example, 1000 DPI (dots per inch which denotes the resolution) so as to first reduce the capacity of data for generating a character for the purpose of making a high resolution output.
In a case of 1000 DPI, the number of pixels per character (the total number of dots theorically allocated) is 140.times.140 when the font size is 10 points which is an ordinary size for a text. If one dot is allocated to one bit in the above-described dot font character generating method, a capacity of 2,450 bytes (140.times.140/8) for one character is required. However, it can be contracted to 1/5 to 1/10 of that quantity in accordance with the outline font method.
On the other hand, in a case where a bit map character is output from the above-described high resolution output device by the outline font method, there arises no critical problem of a quantization error which takes place as a result of calculations for mathematically enlarging or contracting the above-described coordinate value of the control point. That is, the accuracy in the reproduced character image and the quality of the reproduced image have not encountered any such problem.
However, the above-described print processing system arranged in accordance with the electronic method is considerably different from the hardware structure of the great size system in that it is arranged to be adapted to a work station for personal use. Therefore, the hardware must meet a desire of reducing the overall cost while realizing satisfactory performance. That is, the above-described small and precise page printer is, for example, a laser printer capable of outputting B4 sheets at 400 DPI. In this case, it suffers from the small number of pixels which can be allowed for each character. For example, in a case of a printer of 400 DPI, the number of pixels per 10-point character is 56.times.56, while the same is 44.times.44 in the case of an 8-point size. Therefore, the above-described influence of the quantization error becomes more critical in an output device of a low resolution.
Therefore, a first problem arises in that the quality of the output bit map character deteriorates in a case of the resolution of the page printer of the above-described print processing system arranged in accordance with the electronic method and the conventional outline font method, the quality deterioration being exemplified by a problem of excessive thickening of lines constituting the character, irregular line widths, oblique spaces between lines, zigzag curves and an unsatisfactory level of the realized symmetry. In particular, the above-described problems become more critical in a case of the font size which is usually used for a text.
A second problem arises in that the resolution possessed by a monitor display usually is, for example, about 100 DPI, which is lower than the resolution of the above-described printer, although there is a desire of employing a common character outputting method which does not depend upon the resolution of the devices such as the printer and the monitor display for the purpose of realizing the WYSIWYG, which is necessary to improve the document processing software.
In a case of a 100 DPI monitor display, the number of pixels per character of 10-point size is 14.times.14, while the same is 11.times.11 in a case of a character of 8-point size.
It has been known that 16.times.16 pixels: with which the type of the character can be discriminated (however, a complicatedly formed character must be simplified) and 24.times.24 pixels: with which the Ming type and Gothic type can just be distinguished from each other are necessary to form a dot-imaged kanji.
Accordingly, it has been disadvantageous in a case of the font size for a text because of the number of pixels if characters are imaged in accordance with the outline font method and by using a monitor display of about 100 DPI. That is, the deterioration in the quality of the output bit map character becomes more critical with respect to the case of the above-described first problem. Therefore, a critical problem has arisen when WYSIWYG is intended to be realized. Hitherto, an arrangement has been therefore employed in which individual character processing methods or systems are provided for, for example, the monitor display and for the printer in accordance with the resolution of the output device to be connected. As an alternative to this, they are individually provided for each number of pixels per character.
However, there arises a necessity in the above-describe system in that each of the fonts must be simultaneously changed to correspond to an improvement of the system such as the increase in the number of the types of the fonts. If the above-described change is not performed, a problem arises in that the character displayed on the monitor display becomes different from that output from the printer.
Furthermore, there is a system which does not employ the outline font method in the monitor display thereof and in which a pseudo enlargement and-contraction-are performed by means of the dot font to display the character. However, another problem arises in that the final image, which is a critical factor in performing a layout of the page, cannot be completely confirmed.
As described above, there arises a critical technological problem when the outline font method is, to meet the desire of realizing WYSIWYG, used as a common character output method which does not depend upon the resolution of the devices to be connected including the low resolution monitor display. Furthermore, the conventional methods for use to overcome the above-described problem encounter a variety of problems.
A third problem arises in that an addition of correction data, with which a forcible correction is performed for the purpose of absorbing in the visible level of the quantization error due to the calculations for mathematically enlarging or contracting the coordinate value of the control point, will require an excessively large amount of human work to carry out at the addition of the correction data to each of the characters. Furthermore, the conventional character data property established in accordance with the conventional outline font method cannot used.